Fix pkg-name in find_package_handle_standard_args

For the MySQL package find_package_handle_standard_args got passed "MYSQL" as the package name, which differs from
the actual package name. Due to this cmake (3.18) emitted a warning.
This commit fixes this issue by also passing "MySQL" to find_package_handle_standard_args.

Fixes pocoproject#3066

cmake/FindMySQL.cmake

@@ -104,14 +104,14 @@ endif()
 
 set(MYSQL_VERSION ${PC_MYSQL_VERSION})
 
-find_package_handle_standard_args(MYSQL
+find_package_handle_standard_args(MySQL
   FOUND_VAR MYSQL_FOUND
   REQUIRED_VARS
 	MYSQL_INCLUDE_DIR
 	MYSQL_LIBRARY
 	VERSION_VAR MYSQL_VERSION
 )
-
+ 
 if(MYSQL_FOUND)
 	set(MYSQL_LIBRARIES ${MYSQL_LIBRARY})
 	set(MYSQL_INCLUDE_DIRS ${MYSQL_INCLUDE_DIR})